Apache Corp. announced that its Tonto oil field in the United Kingdom sector of the North Sea commenced production on April 24, 2013. Tonto-1, the first producing well, came on stream at an initial rate of 10,346 b/d. Apache holds a 100% working interest in the Tonto Field.
Tonto-1 was drilled as a deviated well from the Forties Bravo production platform. The appraisal wellbore encountered 62 ft of net oil pay in an Eocene-aged sandstone reservoir at a depth of 6,325 ft, which was followed by a horizontal completion lateral that logged 243 ft (measured depth) of net oil pay.
"Seismic inversion processing unlocked pay in the Tonto field, which lies above the main Forties Paleocene reservoir," said James L. House, Apache's regional vice president for the North Sea. "We penetrated Tonto several times in wells targeting Forties. New seismic techniques enabled Apache's North Sea geoscience team to gain a better understanding of Tonto and establish a development plan."
House noted that Apache has been working closely with the UK government to commence production ahead of a new 3-D seismic survey that will be acquired over Forties in July 2013. Tonto oil reserves produced in advance of this survey will allow geoscientists to image production patterns within the Eocene reservoir to optimize the placement of future Tonto producers. Drilling of an additional development well is currently planned by year-end 2013 following analysis of the 4-D (time lapse) seismic data.
Tonto follows Maule and Bacchus as the third new oil field brought online by Apache in the Forties area within the last three years. All three of these developments have qualified under the UK government's small field allowance system, which provides economic incentives for operators to bring these discoveries into production.